MultiscaleTopographicPositionImage of DEM

We follow the paper by J.B.Lindsay, J.M.H.Cockburn, H.A.J.Russell titled An integral image approach to performing multi-scale topographic position analysis to obtain a MultiscaleTopographicPositionImage map of continental Australia at 90m and 30m resolution.

MaxElevationDeviation

We also use the WhiteboxBoxTools software for creating local, meso, broad range MaxElevationDeviation.

Conversion of GeoTiffs to ArcGIS .flt and .bil formats

We have an bash script to convert commonly used geotif format into .flt format data required by WhiteBoxTools. Our script uses gdal and also outputs an intermediate .bil binary format data, also commonly available via ArcGIS.

Steps to MultiscaleTopographicPositionImage

1. Convert GeoTiff into .flt:

   ./tif_to_flt.sh foo bar

This script reads in a GeoTiff named foo.tif, and outputs a bar.flt and a bar_bil.bil with the corresponding header and projection files.

This conversion has been tested using the tests/test_bil.py file. To run the tests, use pytest tests/test_bil.py.

2. Produce MaxElevationDevation images from DEM:

The script multiscale.sh produces the three local, meso and broad range MaxElevationDevation outputs. Use it as the following:

./multiscale.sh dem

3. Combine the three scales into RGB:

The three outputs are combined in this step to produce the multibanded RGB image following this excerpt from the paper by Lindsay et. al.:

The MTPCC image was created by combining the DEV max rasters of the local-,
meso-, and broad-scale ranges into the respective blue, green, and red
channels of a 24-bit color image. The three DEV max rasters were first
processed to linearly rescale their absolute grid cell values within the
range 0–2.58 to the output 8-bit range of 0–255. Grid cells occupying an
average landscape position within a particular range were therefore assigned
the lowest values after rescaling. Highly deviated locations (i.e.
exceptionally elevated or depressed sites) with input pixel values greater
than the 2.58 cutoff value were assigned an output value of 255. The cutoff
value of 2.58 was selected because the ±2.58 standard deviation from the
mean of a Gaussian distribution includes nearly 99% of the samples.

Here is how to use this script:

python multiscale_topographic_position_image.py -l dem_mag1.flt \
    -m dem_mag2.flt -b dem_mag3.flt -i dem.tif -o multiscaled_dem.tif    

The above will output a multiscaled_dem.tif, which is a RGB banded 8 bite (0-255) integer for all three colours.

All in one

The three scripts above are combined into the the multiscale_all_in_one.sh. Use it with the input dem.tif geotif as the following (without the .tif).

./multiscale_all_in_one.sh dem

The final result of this will be multiscaled_dem.tif with projection and georeferencing information copied from the input dem.tif.

Required softwares

One will need to install WhiteboxBoxTools, gdal and need python with the following packages:

GDAL (this is the python binding for system installed gdal)
numpy
pytest (if testing)

Also create a symlink to the whitebox_tools:

sudo ln -s /path/to/whitebox-geospatial-analysis-tools/whitebox_tools/target/release/whitebox_tools /usr/local/bin/whitebox_tools

ArcGIS .flt/.bil to geotif

We also provide a script for conversion of ArcGIS .flt or .bil file into geotif. Run this script as:

$ python flt_to_tif.py -i dem_mag1.flt -o dem_mag1.tif -r dem.tif